Engine turning gear



Filed Dec. 11, 1952 Jan. 19,1954- R. P. HEWSON 2,666,331

ENGINE TURNING GEAR I 2 Sheets-Sheet 1 Jan. 19, 1954 R. P. HEWSON ENGINETURNING GEAR 2 Shets-Sheet 2 Filed Dec. 11, 1952 Wbbar?" P H WSanPatented Jan. 19, 1954 to The Stanley Engmeermg Egh'am, England CompanyLimited;

Applicatidn December 11, 1952, Serial No. 325,260

filaims priority application Great firitain January 9, 1952 Thisinvention relates to engine aiming g ar and has for its main objec't toprovide an impr'bved mini of turning gear for effecting the starting ofan internal combustion engine.

The invention is mainly suitable for use with light engines, and is thusparticularly applicable to internal combustion engines for use ininvalid carriages, motor cycles, motor cars and other light vehicles.

The invention consists in a turning mechanism for starting internalcombustion engines, comprising a belt drive for coupling the engineshaft with a starter device, said belt drive passing round a drivingpulley adapted to move longitudinally in response to rotation by saidstarter device, and a driven pulley associated with said engine shaft,said driven pulley being formed in two parts, one of which is freelymounted and the other of which is keyed to the engine shaft whereby thebelt drive is adapted to move from one part of said pulley to the otherpart in response to the longitudinal movement of said driving pulley andthereby effect the turning of the engine shaft.

According to the preferred arrangement, the part of the driven pulleywhich is keyed to the engine shaft forms part of the engine flywheel,and the freely mounted part of the pulley is mounted in bearings carriedon the engine shaft.

The invention will be more completely understood from the followingdetailed description which is given in conjunction with the accompanyingdrawings, in which:

Figures 1 and 2 are front and fragmentary side views respectively of aninternal combustion engine which is suitable for use in an invalidcarriage, motor cycle, car or other light vehicle, and in which theinvention is embodied.

Referring now to these drawings, the engine shown is constructed insubstantially orthodox form, comprising a main supporting frame I onwhich is mounted a cylinder 2, a carburetor 3, a crank case 4, and anelectric starter device 5 of any well known form, this starter devicebeing secured in position in such .a way that the driven shaft 6 of thestarter device is disposed substantially parallel to the engine shaft I.The driven shaft 6 of the starter device 5 extends some distance beyondthe starter device casing and part of this shaft is provided with ahelical thread 8 on which is mounted a V-shaped pulley 9 preferablyformed of cast iron, this pulley having an internal helical thread Iengaging with the helical thread 8 on the shaft so that this pulley 9 isadapted to rotate with the shaft 6 when the latter is driven by thestarter but is also 6 claims. (01. 74:7)

2 adapted to slide along the shaft in respohse tc relative rotationbetween the shaft and thepul137 as determined by the helical thread.This pulley 9 constitutes the driving pulley of the turning gear and isadapted to be coupled to the engine shaft l by a driving belt II whichpasses round this pulley 9 and also round a second or driven pulleymounted on the engine -shaft. This latter pulley, however, is formed intwo parts I2 and I3, and each part is of sufficient width to earl? thedriving belt II which is thus free to slide from one part of the pulleyto the other. One part I3 of this pulley is formed as an extension ofthe flywheel I4 so that it is permanently keyed to the engine shaft soas to rotate with it, but the other part I2 is freely mounted forindependent rotation and is conveniently mounted in bearings I4 disposedin a ball race I5 secured by bolt I6 to an internal shaft I! screwedinto the interior of the engine shaft I on which the flywheel I4 ismounted.

The driving and driven pulleys are so relatively positioned that whenthe engine is stationary the freely mounted part I2 of the driven pulleyis disposed immediately. opposite or below the driving pulley 9 so thatthe belt is perfectly free to rotate. When, however, currendis appliedto the starting device 5, e. g. by the pressing of a button or theclosure of a switch, the sudden rotation of the shaft 6 of the starterdevice acting against the inertia of the aforesaid driving pulley 9causes the latter to slide inwards along the helical thread 8, thuscausing the driving belt I I to slide on to the part I3 of the drivenpulley formed on the engine flywheel and thus rotate the latter. As soonas the engine starts up, however, and current is disconnected from thestarter device 5, the driving pulley 6 will slide back into its originalposition and cause the driving belt I I to slide back on to the freelymounted part I2 of the driven pulley, thereby allowing the engineflywheel and shaft to run freely and leaving the starter gear inreadiness for the next operation with the belt I I and associatedpulleys stationary.

It will thus be seen that by means of this arrangement a very smoothform of starter mechanism is provided, and the customary banging whichnormally takes place by a pinion wheel being flung into engagement withthe flywheel teeth of the engine is entirely obviated. Moreover, in viewof the fact that the driving belt and 7 its associated pulleys remainsstationary except when it is in actual operative movement, all un- 5necessary wear on the driving belt is substantially eliminated.

I claim:

1. Engine turning mechanism for starting internal combustion engines,comprising a belt drive for coupling the engine shaft with a starterdevice, said belt drive passing round a driving pulley adapted to movelongitudinally in response to rotation by said starter device, and adriven pulley associated with said engine shaft, said driven pulleybeing formed in two parts, one of which is freely mounted, and the otherof which is keyed to the engine shaft, whereby the belt drive is adaptedto move from one part of said pulley to the other part in response tothe longitudinal movement of said driving pulley and thereby effect theturning of the engine shaft.

2. Engine turning mechanism for starting internal combustion engines,comprising a belt drive for coupling the engine shaft with a starterdevice, said belt drive passing round a driving pulley adapted to movelongitudinally in response to rotation by said starter device, and oneor other of two pulleys disposed adjacent one another, one of suchdriven pulleys being freely mounted, and the other being formed on theengine flywheel, the belt drive being free to move from one drivenpulley to the other in response to the longitudinal movement of saiddriving pulley so as to effect the turning of the engine flywheelandshaft.

3. Engine turning mechanism according to' corresponding helical threadon the shaft of said starter device, whereby relative rotation betweenthe shaft and the pulley effected by said starter device, brings about alongitudinal movement of the pulley with respect to the shaft.

6. Engine turning mechanism according to claim 1, wherein said drivingpulley is so arranged as to be disposed substantially opposite thefreely mounted part of said driven pulley when the engine is stationary,whereby the longitudinal movement of said driving pulley brought aboutby said. starter device causes said belt drive to move over. from thefreely. mounted part of said driven pulley on to the part keyed to theengine shaft.

ROBERT PHILIP HEWSON.

References Cited in the file of this patent UNITED STATES PATENTS Number

